OT: Mirrored or RAID5

[Koopmann, Jan-Peter]

> R1 gives better performance than R5, for both
> writes and reads. Combining striping (sometimes called R0) with
> mirroring (called R1+0) will give you the best performance.
> As a stopgap, you can have a large cache on your Raid controller, in
> which case small I/O loads will never really depend on the disks, so
> then an R5 can be acceptable.

I do not think this is true in all cases. It really depends on your
hardware and what kind of data is read. If you have a really good RAID
controller it will do the RAID5 checksums wire-speed. In that case
having many hard disks can and will give you better performance than
"just" two disks and a RAID-1 set, depending on the discs etc. Reading
from 10 disks will give you quite a throughput. :-) Moreover RAID-5 is
quite good in reading chunks of data in multi-user environments. 

I agree though: A 10 disk RAID-10 will probably outperform a 10 disk
RAID-5 in most cases.